Solid propellants with biradical burning rate catalysts

ABSTRACT

Disclosed are p, p&#39;&#39;-biphenylene-bis(diphenylmethyl) and p, p&#39;&#39;phenylene-bis(diphenylmethyl) as the means for achieving high burning rates of solid propellant compositions. The disclosed means for achieving high burning rates are compounds which exist in the biradical form and contain two trivalent carbon atoms in each molecule which contains a quinoid structure based on paramagnetic susceptibility measurements. The disclosed biradical compounds may be used to enhance the burning rate of crosslinkable double-base propellants. Representative crosslinkable double-base propellants using the biradical compounds are disclosed. Also, disclosed are representative hydroxyl-terminated polybutadiene (HTPB)-based propellants and carboxyl-terminated polybutadiene (CTPB)-based propellants which employ the biradical compound as catalyst. Processing aids (e.g., lecithin), stabilizers, and curatives may be used in minor amounts in the basic formulation or as additives to the propellant composition.

[ Oct. 21, 1975 SOLID PROPELLANTS WITH B IRADICAL BURNING RATE CATALYSTSAppl. No.: 78,331

[44] Published under the Trial Voluntary Protest Program on January 28,1975 as document no. B 78,331.

[52] US. Cl. l49/19.8; 149/19.9; 149/44; 149/76; 149/92 [51] Int. Cl.C06D 5/06 [58] Field of Search 149/19, 44, 76, 60, 61, 149/83, 92, 97,100, 19.8, 19.9

[56] References Cited UNITED STATES PATENTS 3,203,842 8/1965 Godfrey149/76 X 3,364,086 1/1968 Oversohl et al... 149/76 X 3,400,025 9/1968Hopper et al 149/92 X 3,455,883 7/1969 Kamal et al 260/775 3,476,62211/1969 Harada et al. 149/19 3,498,856 3/1970 Harris 149/19 3,585,0906/1971 7 Sayles 149/19 Primary Examiner-Benjamin R. Padgett AssistantExaminer-E. A. Miller Attorney, Agent, or FirmNathan Edelberg; Robert P.Gibson; Jack W. Voigt ABSTRACT Disclosed are p,p-biphenylene-bis(diphenylmethyl) and p,p'-phenylene-bis(diphenylmethyl) as the means for achieving high burningrates of solid propellant compositions. The disclosed means forachieving high burning rates are compounds which exist in the biradicalform and contain two trivalent carbon atoms in each molecule whichcontains a quinoid structure based on paramagnetic susceptibilitymeasurements. The disclosed biradical compounds may be used to enhancethe burning rate of crosslinkable double-base propellants.Representative crosslinkable double-base propellants using the biradicalcompounds are disclosed. Also, disclosed are representativehydroxylterminated polybutadiene (HTPB)-based propellants andcarboxyl'terminated polybutadiene (CTPB)-based propellants which employthe biradical compound as catalyst. Processing aids (e.g., lecithin),stabilizers, and curatives may be used in minor amounts in the basicformulation or as additives to the propellant composition.

8 Claims, N0 Drawings SOLID PROPELLANTS WITH BIRADICAL BURNING RATECATALYSTS BACKGROUND OF THE INVENTION Catalysis or means for promotingthe burning rates of propellants permits the expulsion of a largeramount of energy over a shorter period of time to thereby result in ahigher specific impulse or force to perform a desired function bypropulsion means. In many instances the use of a relatively smallamountof a catalyst material (e.g., 1-2% by weight) enables one to change aslower burning propellant into a faster burning propellant.

Catalyst materials of the prior art include iron oxide,

copper oxide, copper chromite, the organoiron compound (ferrocene andits derivatives), and other organometallic compounds. More recentlycarborane and carborane derivatives have been investigated as catalystmaterials for propellants.

Biradical compounds have been studied by Schonberg, Trans. Faraday Soc.32, 515 (1936).

The present invention deals with earlier studied compounds which existentirely in the biradical form. More particularly the present inventiondeals with specific biradical compounds which have been found to beuseful as burning rate catalysts for solid propellant compositions.

Therefore, an object of this invention is to provide biradical compoundswhich are useful as burning rate catalysts for solid propellants.

Another object is to provide solid propellant formulations of thecrosslinkable double-base type which utiliZe a biradical compound whichfunctions as a burning rate catalyst and a ballistic modifier to inhibitresonance burning and combustion instability.

Another object of this invention is to provide hydrox- SUMMARY OF THEINVENTION The catalyst of this invention is selected from the biradicalcompounds, p, p-biphenylene-bis(diphenyl- 5 methyl) and p,p'-phenylene-bis(diphenylmethyl). The

' composition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The biradical compound p,p'-biphenylene-bis(diphenylmethyl) (referred to for simplicity ascompound A) 'is illustrated by the following structural formula:

wherein Ph is the abbreviation for phenyl, C l-I The biradical compoundp, p'-phenylene-bis(diphenylmethyl) (referred to for simplicity ascompound B) is illustrated by the following structural formula:

wherein Ph is the abbreviation for phenyl, C6H

Table I illustrates how the biradical burning rate catalyst of thisinvention is used in a crosslinkable double- Ph C CPhg

PhzC

CPh

base propellant formulation.

Table I A Comparison of Crosslinkable Double-Base Propellants With andWithout Burning Rate INGREDIENTS/BURNING RATE Catalyst PROPELLANTCOMPOSITIONS PERCENT BY WEIGHT AND BURNING RATES A B C Casting Powder(binder) ll.25 11.25 .25 Triethylene Glycol Dinitrate (TEGDN) 28.7528.75 28.75 Butanetriol Trinitrate (B'ITN) l5.5 15.5 15.5Cyclotetramethylenetetranitramine (HMX) 40.0 40.0 36,0 Lead Peroxide 4.04.0 p,p'-Biphenylene-bis(diphenylmethyl) 4.0 4.0 Resorcinol 0.5 0.5 0.5Toluene Diisocyanate (added) 1.0 1.0 1.0 Burning Rate (ips at 1000 psi)1 0.35 0.72 0.85

*Casting powder formulation: l0.l parts nitrocellulose .95 partsnitroglycerine .20 parts 2-nitrodiphenylamine TOTAL I 1.25 parts Castingpowder The biradical catalysts are effective both as burning ratepromoters as well as inhibitors for resonance burnyl-terminatedpolybutadiene-based propellants which employ a biradical compound as theburning rate catalyst. 1

. Still another object of this invention is to providecarboxl-terminated polybutadiene-based propellants which employ abiradical compound as theburning rate catalyst.

3 (ballistic modifier and catalyst), resorcinol (stabilizer), andtoluene diisocyanate (crosslinking agent). Al

a carboxyl-terminated polybutadiene-based propellant.

Table 111 A Comparison of a Carboxyl-Terminated Polybutadiene-BasedPropellant (CTPB) Using N-Butylferrocene as Burning Rate Catalyst With aCTPB-Based Propellant Using Biradical Burning Rate Catalyst though,compositions A and C of Table l are near smokeless double-basepropellants, an improvement in the smokeless properties is gained incomposition B where a complete replacement of lead peroxide is made byp, p'-biphenylene-bis(diphenylmethyl).

Table 11 illustrates how the biradical burning rate cat- 30 alyst(compound A or B) of this invention is used in a hydroxyl-terminatedpolybutadiene-based propellant.

Table 11 The propellants of Table 111 employ a'carboxyl-terminatedpolybutadiene binder, ammonium perchlorate oxidizer, aluminum metalfuel, n-butylferrocene catalyst (in standard composition A) and p,p'-biphenylene-bis(diphenylmethyl) (in composition B), and crosslinkingagent tris[l-(2-methyl)aziridinyl]-phosphine oxide.Tris(oxiranyl)-para-aminophenol and iron linoleate are curatives each ofwhich are added in trace A Comparison of Hydroxyl-TerminatedPolybutadiene-Based Propellants With and Without Biradical Burning RateCatalyst PROPELLANT COMPOSITION INGREDIENTS/BURNING RATE PERCENT BYWEIGHT AND BURNING RATES INGREDIENT Hydroxyl-terminated PolybutadienePrepolymer 9.84 9.84 Dimeryl Diisocyanate 1.92 1.92 Bonding Agent* 0.240.24 Ammonium Perchlorate 73. 71. Aluminum 15. 15.p,p'-Biphenylene-bis(diphenylmethyl) 2. Burning Rate (ips at 1000 psi)0.35 0.78

Bonding agent is formulated of cquimnlar quantities of trisl 1-(Z-methyl)aziridinyllphosphine oxide. tartaric acid. and adipic acid.Bonding agent is used in an amount from about 0.1-0.3 percent by weightof propellant composition.

The propellants of Table I] employ a hydroxyl-terminated polybutadienebinder, ammonium perchlorate oxidizer, aluminum metal fuel, the burningrate catalyst p, p'-biphenylene-bis(diphenylmethyl), and materials foradditives which include the crosslinking compound dimeryl diisocyanateand a bonding agent to provide desirable physical properties throughcrosslinking and curing reactions. A marked increase in burning rate isachieved with Propellant B of Table I1 which contains the burning ratecatalyst, p, p-biphenylene-bis(diphenylmethyl). Propellant A of Table IIis the standard propellant. The use of the biradical catalyst to controlburning rates of HTPB-based propellants is attractive because of thecompatibility of this type compound with HTPB-based propellants.

Table III illustrates how the biradical burning rate catalyst (compoundAor B) of this invention is used in amounts from about 0.1 to about 0.5percent by weight of the total weight of all the other combinedpropellant ingredients.

The ranges of propellant ingredients of the doublebase type propellantsdisclosed herein are (in percent by weight of the propellantcomposition) as follows: binder from casting powder (formulated ofnitrocellulose of about 10.1 parts, of about 0.95 parts nitroglycerine,and of about 0.20 parts Z-nitrodiphenylamine) from about 6.to about 23;TEGDN from about 20 to about 35; BTTN from about 10 to about 20; HMXfrom about 30 to about 50; biradical catalyst (selected from p,p-biphenylene-bis(diphenylmethyl) and p,p'-phenylene-bis(diphenylmethyl)) from about 2.0 to'about 8.0; leadperoxide from about 2.0 to about 6.0; stabilizers from about 0.5 toabout 1.0; and curative additives from about 0.5 to about 2.0.

foregcrosslinking functions, bonding agent. functions,

curing functions, etc. from about 0,5,to-about 2.0.

The ranges of the composite propellant ingredients, usingcarboxylterminated polybiitadiene binder in the compositions disclosedherein, are )(in percent by weight" of the p'ropellant composition) asfollows: biradical catalyst selected from pj'pFbiphenylene-bisbcliphenylm'e'thylji'and p'-phenylene-bis(diphenylmethyl) from about 2.0to about 8.0;ariinibnjiiim perchlorate from about 60 to about'70;aluminum metal fuel from about 5 to "about20; carboxyl-terminatedpolybutadi'ene prepo'lyrner' from about? to about crosslinking agent(tris[ 1-( 2-methyl)aziridiny1]phosphine oxide) from about 0.5 to about2.0; and curatives (tris(oxiranyl)-para-aminophenol) and iron linoleate,each in an amount from about 0.1 to about 0.5 percent by weight of thetotal weight of all the other propellant ingredients.

Because of the compatibility of the biradical compounds of thisinvention with both double base-propel- I lant ingredients and compositepropellants using hy-' any unavailability of facilities for themanufacture of the boron-containing catalysts.

No special procedures are required for the mixing of propellantsemploying the disclosed biradical compounds. The standard methods orprocedures employed in the art for propellant mixing of double-base andcomposite propellants have been proven to be very satisfactory for thepropellants of this invention.

I claim:

1. A solid propellant composition comprising a binder, an oxidizer, aburning rate catalyst selected from the biradical compounds consistingof p, p-biphenylene-bis(diphenylmethyl) and p, p-phenylene-bis(-diphenylmethyl), and a crosslinking agent.

2. The propellant composition of claim 1 wherein said binder is presentin an amount from about 6 to about 23 percent by weight of saidpropellant composition, said binder being constituted of about 10.1parts nitrocellulose, about 0.95 parts nitroglycerin, and about 020parts of 2-nitrodiphenylamine; said oxidizer iscyclotetramethylenetetranitramine which is present in an amount fromabout 30 to about 50 percent by weight of said propellant composition;said catalyst selected is p, p-biphenylene-bis(diphenylmethyl) whichclotetramethylenetetranitramine --is present .6 V ispresent in an amountfrom about 2 to about 8'percent by weight of said.propellantcomposition;said composition includes the plasticizer, triethylene glycol dinitratein an amount from about 20 to about 35 percent by weight of saidpropellant composition and the plasticizer, butanetriol'trinitrate in anamount from about 10 to about 20percent by weight of said propellantcomposition; said propellant composition additionally incl'udesan agentfor stabilizingwhich is resorcinol which is presentin an amount fromabout 0.5 to about 1.0 percent by weight of said propellantcomposition;and wherein said crosslinking agent is toluene diisocyanate which isaddedin an'amount of about 1.0 percent by weight of the total weight ofall the other propellant ingredients.

3: The propellant compositionof claim 2 wherein said binder is presentin an amount of about 1 1.25 percent b-y'weight of said propellantcomposition; said eyin an amount of about 36 to about '40 percent byweight of said propellant composition; said triethylene glycol dinitrateis present-in an amount of about 28.75 percent by weight of saidpropellant composition; said butanetriol trinitrate is present in anamount of about 15.5 percent by weight of said propellant composition;said p, p'-biphenylene-bis(diphenylmethyl) is present in an amount ofabout 4.0 percent by weight of said propellant composition; and saidresorcinol is present in an amount of about 0.5 percent by weight ofsaid propellant composition.

4. The propellant composition of claim 3 wherein saidcyclotetramethylenetetranitramine is present in an amount of about 36percent by weight of said propellant composition; and wherein saidcomposition additionally contains the ballistic modifier, lead peroxide,in an amount of about 4.0 percent by weight of said propellantcomposition.

5. The propellant composition of claim 1 wherein said binder ishydroxyl-terminated polybutadiene which is present in an amount fromabout 7 to about 15 percent by weight of said propellant composition;said oxidizer is ammonium perchlorate which is present in an amount fromabout to about percent by weight of said propellant composition; saidcatalyst selected is p, p'-biphenylene-bis(diphenylmethyl) which ispresent in an amount from about 2 to about 8 percent by weight of saidpropellant composition; said crosslinking agent is dimeryl diisocyanatewhich is present in an amount from about 0.5 to about 2.0 percent byweight of said propellant composition; said composition contains abonding agent formulated of equimolar quantities oftris[1-(2-methyl)-aziridinyl]phosphine oxide, tartaric acid, and adipicacid, said bonding agent is present in an amount from about 0.1 to about0.3 percent by weight of said propellant composition; and wherein saidpropellant composition additionally contains aluminium metal fuel in anamount from about 5 to about 20 percent by weight of said propellantcomposition.

6. The propellant composition of claim 5 wherein said binder is presentin an amount of about 9.84 percent by weight of said propellantcomposition; said ammonium perchlorate is present in an amount of about71 percent by weight of said propellant composition; said p,p'-biphenylene-bis(diphenylmethyl) is present in an amount of about 2percent by weight of said propellant composition; said dimeryldiisocyanate is present in an amount of about 1.92 percent by weight ofsaid propellant composition; said bonding agent is present in an amountof about 0.24 percent by weight of said propellant composition; and saidaluminium metal fuel is present in an amount of about 15 percent byweight of said propellant composition.

7. The propellant composition of claim 1 wherein said binder iscarboxyl-terminated polybutadiene which is present in an amount fromabout 7 to about l percent by weight of said propellant composition;said oxidizer is ammonium perchlorate which is present in an amount fromabout 60 to about 70 percent by weight of said propellant composition;said catalyst selected is p, p'-biphenylene-bis(diphenylmethyl) which ispresent in an amount from about 2 to about 8 percent by weight of saidpropellant composition; said crosslinking agent is tris[l-(2-methyl)aziridinyl]-phosphine oxide which is present in an amountfrom about 05 to about 2.0 percent by weight of said propellantcomposition; said propellant composition includes aluminum metal fuel inan amount from about 5 to about percent by weight of said propellantcomposition; and wherein said propellant composition additionally in- 8cludes the curatives consisting of tris(oxiranyl)-paraaminophenol andiron linoleate which are each added to said propellant composition in anamount from about 0.1 to about 0.5 percent by weight of the total weightof all the other propellant ingredients.

8. The propellant composition of claim 7 wherein said binder is presentin an amount of about 12.5 percent by weight of said propellantcomposition; said ammonium perchlorate is present in an amount of about66 percent by weight of said perchlorate composition; saidp,.p'-biphenylene-bis(diphenylmethyl) is present in an amount of about 7percent by weight of said propellant composition; saidtris[l-(2-methyl)aziridinyl]-.

phosphine oxide is present in an amount of about 0.5 percent by weightof said propellant composition; said aluminium metal fuel is present inan amount of about 14 percent by weight of said propellant composition;and said tris(oxiranyl)-para-aminophenol and iron linoleate are eachpresent in an amount of about 0.1 percent by weight of all the otherpropellant ingredients.

1. A SOLID PROPELLANT COMPOSITION COMPRISING A BINDER, AN OXIDIZER, ABURNING RATE CATALYST SELECTED FROM THE BIRADICAL COMPOUNDS CONSISTINGOF P, P''-BIPHENYLENE-BIS(DIPHENYLMETHYL) AND P,P''-PHENYLENE-BIS(DIPHENYLMETHYL), AND A CROSSLINKING AGENT.
 2. Thepropellant composition of claim 1 wherein said binder is present in anamount from about 6 to about 23 percent by weight of said propellantcomposition, said binder being constituted of about 10.1 partsnitrocellulose, about 0.95 parts nitroglycerin, and about 0.20 parts of2-nitrodiphenylamine; said oxidizer is cyclotetramethylenetetranitraminewhich is present in an amount from about 30 to about 50 percent byweight of said propellant composition; said catalyst selected is p,p''-biphenylene-bis(diphenylmethyl) which is present in an amount fromabout 2 to about 8 percent by weight of said propellant composition;said composition includes the plasticizer, triethylene glycol dinitratein an amount from about 20 to about 35 percent by weight of saidpropellant composition and the plasticizer, butanetriol trinitrate in anamount from about 10 to about 20 percent by weight of said propellantcomposition; said propellant composition additionally includes an agentfor stabilizing which is resorcinol which is present in an amount fromabout 0.5 to about 1.0 percent by weight of said propellant composition;and wherein said crosslinking agent is toluene diisocyanate which isadded in an amount of about 1.0 percent by weight of the total weight ofall the other propellant ingredients.
 3. The proPellant composition ofclaim 2 wherein said binder is present in an amount of about 11.25percent by weight of said propellant composition; saidcyclotetramethylenetetranitramine is present in an amount of about 36 toabout 40 percent by weight of said propellant composition; saidtriethylene glycol dinitrate is present in an amount of about 28.75percent by weight of said propellant composition; said butanetrioltrinitrate is present in an amount of about 15.5 percent by weight ofsaid propellant composition; said p, p''-biphenylene-bis(diphenylmethyl)is present in an amount of about 4.0 percent by weight of saidpropellant composition; and said resorcinol is present in an amount ofabout 0.5 percent by weight of said propellant composition.
 4. Thepropellant composition of claim 3 wherein saidcyclotetramethylenetetranitramine is present in an amount of about 36percent by weight of said propellant composition; and wherein saidcomposition additionally contains the ballistic modifier, lead peroxide,in an amount of about 4.0 percent by weight of said propellantcomposition.
 5. The propellant composition of claim 1 wherein saidbinder is hydroxyl-terminated polybutadiene which is present in anamount from about 7 to about 15 percent by weight of said propellantcomposition; said oxidizer is ammonium perchlorate which is present inan amount from about 65 to about 75 percent by weight of said propellantcomposition; said catalyst selected is p,p''-biphenylene-bis(diphenylmethyl) which is present in an amount fromabout 2 to about 8 percent by weight of said propellant composition;said crosslinking agent is dimeryl diisocyanate which is present in anamount from about 0.5 to about 2.0 percent by weight of said propellantcomposition; said composition contains a bonding agent formulated ofequimolar quantities of tris(1-(2-methyl)-aziridinyl)phosphine oxide,tartaric acid, and adipic acid, said bonding agent is present in anamount from about 0.1 to about 0.3 percent by weight of said propellantcomposition; and wherein said propellant composition additionallycontains aluminium metal fuel in an amount from about 5 to about 20percent by weight of said propellant composition.
 6. The propellantcomposition of claim 5 wherein said binder is present in an amount ofabout 9.84 percent by weight of said propellant composition; saidammonium perchlorate is present in an amount of about 71 percent byweight of said propellant composition; said p,p''-biphenylene-bis(diphenylmethyl) is present in an amount of about 2percent by weight of said propellant composition; said dimeryldiisocyanate is present in an amount of about 1.92 percent by weight ofsaid propellant composition; said bonding agent is present in an amountof about 0.24 percent by weight of said propellant composition; and saidaluminium metal fuel is present in an amount of about 15 percent byweight of said propellant composition.
 7. The propellant composition ofclaim 1 wherein said binder is carboxyl-terminated polybutadiene whichis present in an amount from about 7 to about 15 percent by weight ofsaid propellant composition; said oxidizer is ammonium perchlorate whichis present in an amount from about 60 to about 70 percent by weight ofsaid propellant composition; said catalyst selected is p,p''-biphenylene-bis(diphenylmethyl) which is present in an amount fromabout 2 to about 8 percent by weight of said propellant composition;said crosslinking agent is tris(1-(2-methyl)aziridinyl)-phosphine oxidewhich is present in an amount from about 0.5 to about 2.0 percent byweight of said propellant composition; said propellant compositionincludes aluminum metal fuel in an amount from about 5 to about 15percent by weight of said propellant composition; and wherein saidpropellant composition additionally includes the curatives consisting oftris(oxiranyl)-para-aminophenol and iron linoleate which are each addedto said propellant composition in an amount from about 0.1 to about 0.5percent by weight of the total weight of all the other propellantingredients.
 8. The propellant composition of claim 7 wherein saidbinder is present in an amount of about 12.5 percent by weight of saidpropellant composition; said ammonium perchlorate is present in anamount of about 66 percent by weight of said perchlorate composition;said p, p''-biphenylene-bis(diphenylmethyl) is present in an amount ofabout 7 percent by weight of said propellant composition; saidtris(1-(2-methyl)aziridinyl)phosphine oxide is present in an amount ofabout 0.5 percent by weight of said propellant composition; saidaluminium metal fuel is present in an amount of about 14 percent byweight of said propellant composition; and saidtris(oxiranyl)-para-aminophenol and iron linoleate are each present inan amount of about 0.1 percent by weight of all the other propellantingredients.